Return flow carburetor



May 24, 1966 T. M. BALL 252,498

RETURN FLOW CARBURETOR Original Filed July 28, 1959 IN VENTOR.

United States Patent 3,252,498 RETURN FLOW CARBURETOR Thomas M. Ball, Bloomfield Hills, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Original applications July 28, 1959, Ser. No. 830,007, now Patent No. 3,161,700, dated Dec. 15, 1964, and July 28, 1959, Ser. No. 830,124, now Patent No. 3,165,561, dated Jan. 12, 1965. Divided and this application Apr. 5, 1963, Ser. No. 270,985 The portion of the term of the patent subsequent to Feb. 19, 1980, has been disclaimed 6 Claims. (Cl. 15836.4)

This application is a division of copendin-g applications Serial Nos. 830,007 and 830,124, filed July 28, I 1959, now Patent Nos. 3,161,700, issued December 15,

1964, and No. 3,165,561, issued January 12, 1965, respectively, which are continuations-in-part of copending application Serial No. 816,529, now Patent No. 3,078,077. This invention relates to improvements in a carburetor particularly adapted for use with an automobile internal combustion engine.

In' conventional carburetors, a float controlled fuel inlet needle valve is employed to regulate the fuel level in the carburetor fuel bowl. Small dirt particles sometimes interfere with effective operation of the valve, as for example by becoming lodged between mating valve seats which otherwise cooperate to regulate the fuel flow into the fu l bowl. Also the floats require considerable size in order to be effective because of the comparatively low specific gravity of the fuel. In consequence the size of i the fuel bowl must be appreciably larger than is. other objections and in particular to provide a floatless car-- buretor which does not require a fuel inlet needle valve. Another object is to provide such a construction including an overflow standpipe in the fuel bowl having an upper opening which determines the maximum fuel level in the bowl. A fuel inlet pump is provided to pump fuel into the bowl at a rate in excess of demand. The excess fuel overflows into the standpipe and is returned to the fuel tank. In order to overcome adverse grade conditions, among other considerations, which prevent the excess fuel from returning to the tank by gravity flow, a scavenging pump is provided in the fuel return line between the overflow standpipe and the tank.

Among other advantages of the above structure, elimination of the necessarily large float enables utilization of a comparatively small fuel bowl closely adjacent the inlet air induction conduits of a multiple barrel carburetor, for example. The small fuel bowl thus located is less sensitive to grade and inertial effects and enables uniform fuel distribution toeach of the several induction conduits. Also recirculation of the fuel drives off its more volatile fuel fractions and thereby minimizes some of the problems of the conventional float controlled carburetor, as for example those concerned with vapor formation.

In order to provide adequate fuel during maximum engine speed at wide open throttle, a fuel inlet pump is provided which delivers an excess supply of fuel to the fuel bowl during all operating conditions of the engine. When the throttle is suddenly closed while the engine is still ice operating at high speed, unless some provision is made to the contrary, a major portion of the fuel supplied to the fuel bowl will be recirculated. In general the life of a fuel pump and in particular the life of an engine driven diaphragm type pump, which is preferred for supplying fuel in the quantity required and at a substantially uniform pressure regardless of changes in engine speed, depends upon the quantity of fuel pumped.

For the above reasons, as well as the desirability of conserving power in an automobile engine and of minimizing fuel heating by excessive recirculation, another object of the present invention is to provide improved simple and highly effective means for supplying fuel to the fuel bowl in reasonable and safe amounts related to engine requirements.

Another object is to provide a carburetor and diaphragm fuel pump combination of the type described wherein the pump comprises a pumping chamber having a movable diaphragm defining one wall thereof. The pumping chamber is provided 'with check valve controlled inlet and discharge ports in communication with a fuel tank and with the fuel bowl respectively and operative so that during movement of the diaphragm in one direction in an intake stroke to enlarge the volume of the pumping chamber, fuel is drawn from the tank into the pumping chamber. During movement of the diaphragm in the opposite direction in a pumping stroke, fuel is discharged from the pumping chamber into the fuel bowl. The diaphragm is secured to a plunger arm for actuation thereby. A pumping spring under compression between the diaphragm and a fixed portion of the pump mechanism yieldingly urges the diaphragm in said opposite direction to cause the pumping stroke. A pivotal arm enga-geable with a rotating cam driven by the automobile engine to be pivotally oscillated thereby is also engageable with the plunger to move the latter in said one direction against the force of the pumping spring to compress the latter. Thepivotal arm is also freely engageable with the plunger so that during the .reverse pivotal movement of the arm, the latter will move independently of the plunger and release the diaphragm for spring urged pumping movement in said opposite direction, but will not positively urge movement of the diaphragm in said opposite direction. In consequence, the pumping force will result entirely-from the compressed pumping spring and will be substantially constant regardless of the speed of the engine or of the pivotally oscillated arm.

Other and more specific objects are to provide such a diaphragm pump and carburetor combination having means for varying the pumping stroke of the diaphragm in said opposite direction by pressure actuated means connected with the discharge side of the scavenging pump.

Other objects of the invention will appear in the following description and appended claims, reference being bad to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIGURE 1 is a schematic mid-sectional view of a' floatless return flow carburetor and pump embodying the present invention showing means actuated by the scavenging pump discharge pressure for controlling the diaphragm pumping stroke.

FIGURE 2 is a view similar to FIGURE 1, but illustrating a modification of the invention.

FIGURE 3 is a fragmentary view similar to FIGURE 2, but illustrating another modification. It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phras-eology or terminology employed herein is for the purpose of descriptlon and not of limitation.

Referring to FIGURES l and 2, the carburetor shown comprises a .cast housing formed to provide an air inlet induction conduit including a venturi portion having a restricted venturi 11 at its upper portion and a throttle blade 12 pivotally mounted on a shaft 13 at a lower portion usually referred to as the throttle body. An upper portion of the casting is formed to provide an air horn 14 adapted to be connected with the usual air filter and opening at its downstream end into the venturi 11 to supply air thereto. The casting portions 10 and 14 are suitably secured together, as for example by screws not shown, and comprise an upper portion of the air inlet and fuel mixing induction system which extends downstream of the throttle valve 12 and discharges into the usual engine cylinders in a conventional manner.

Integral with the casting 10 in the present instance is a fuel bowl casting 15 containing an annular chamber or fuel bowl 16 enclosing a cylindrical standpipe or weir 17 which also serves as an acceleration pump cylinder containing a plunger 18 reci-proca'ble in its lower portion and secured to a plunger shaft 19 for actuation thereby. Where desired the shaft 19 is connected by suitable linkage with a pedal operated accelerator mechanism which controls the opening and closing of valve 12 to operate conjointly therewith. Upon upward movementof plunger 18, fuel is drawn into the lower portion of chamber 17 via conduit 20 in communication with the bowl 16. A suitable check valve illustrated schematically as a ball check element 21 normally seats at'the mouth of the duct 20 opening into the lower portion of chamber 17 to prevent loss of fuel therefrom but is raised from its seat by the fuel flow into chamber 17 on the upstroke of plunger 18.

Upon downward movement of plunger 18 the fuel is forced from chamber 17 into the inducation conduit via acceleration fuel conduit 22, ball check valve 23, and nozzle 24 which latter discharges into the induction conduit at .a location immediately above the throat of venturi 11. The check valve 23 is schematically illustrated as a ball normally urged by a spring to a seated position closing nozzle 24 from the interior of chamber 17, the ball being readily movable upward against the tension of its seating spring by the acceleration fuel pressure upon downward movement of plunger 18. The main fuel to the engine is supplied via duct 25 which opens at its lower end through metering port 26 into the fuel bowl 16 and communicates at its upper end with a fuel nozzle '27 having its discharge orifice located within the throat of venturi 11.

In accordance with the structure described thus far, fuel entering the bowl 16 in excess of engine requirements overflows the upper edge of standpipe 17 which thereby maintains the fuel in the bowl 16 at a predetermined maximum level determined by the effective height of the standpipe 17 without recourse to a float operated mechanism. Fuel is supplied to the bowl 16 from a suitable fuel tank 280 via conduit 28.

A multiple piece fuel pump housing 37 comprising an upper dome 38 and a lower basin 39 cooperate with diphragms 40 and 41 respectively to provide an inlet fuel pumping or working chamber 42 and an exhaust fuel pumping or scavenging chamber 43. Springs 44 and 45 under compression between portions of housing 37 and diaphragms 40 and 41 respectively urge the former diaphragm upward and the latter diaphragm downwardly to effect the pumping strokes for the respective chaimbers 42 and 43.

The upper working chamber 42 comprises a portion of supply duct 28 which communicates upstream of chamber 42 with the fuel tank. Fuel enters and leaves chamber 42 via an inlet port 46 and a discharge port 47 associated with check valves 48 and 49 respectively. Upon downward movement of diaphragm 40 as explained below, fuel is drawn in the direct-ion of the arrow 28a from the tank and through inlet .port 46 into working chamber 42. During this operation ball valve 48 is forced from its seat at port 46 by the fuel flow, and ball valve 49 seats at the discharge port 47 to close the latter from the fuel bowl 16. Upon upward movement of diaphragm 40, ball valve 48 is caused to seat at port 46 to close the working chamber 42 from the fuel tank. During this operation, the pressure exerted in chamber 42 unseats ball valve 49 from port 47 and supplies fuel via conduit 28 to the fuel bowl 16. The spaces at the sides of the diaphragm 40 and 41 opposite chambers 42 and 43 respectively are vented at the atmosphere by ducts 50 and 51 to facilitate the pump operation.

Fuel is returned in the direction of arrow 52a from standpipe 17 to the fuel tank 280 via fuel return conduit 52 which includes chamber 43 as a portion thereof. Upstream, the conduit 52 communicates with standpipe 17 at a location above the uppermost limit of movement of plunger 18. The return fuel enters chamber 43 via port 53 and discharges from chamber 43 via port 54. Ball check valves and 56 are associated with ports 53 and 54 respectively, so that upon upward movement of diaphragm 41 as described below, ball 56 seats against port 54 to close chamber 43 from the fuel tank. During this operation, ball 55 is unseated from port 53 to open communication between chamber 43 and standpipe 17 and to draw fuel from the latter. Upon downward movement of diaphragm 41, ball 55 is seated against port 53 to close chamber 43 from standpipe 17. Simultaneously ball 56 is unseated from port 54 by the pressure in chamber 43 to discharge fuel from the latter in the direction of arrow 52a to the tank. Movement limiting pins in the conduits 28 and 52 associated with the ball valves 48, 49, 55 and 56 prevent undue movement of the check balls from their associated ports.

Inasmuch as the check valves are well known, these are merely shown schematically and are not discussed in further detail.

Actuation of the diaphragms 40 and 41 is accomplished by driving shafts 57 and 58 connected to these diaphragms and terminating in enlarged heads 59 and 60 respectively. Pivotal levers 61 and 62 are pivoted on housing 37 at locations 63 and 64 respectively between their ends. Each lever has one end engaged with a rotating eccentric cam 65 mounted on a shaft 66 driven by the automobile engine. The opposite ends of the levers 61 and 62 are provided with oversized openings 67 and 68 through which the rods 57 and 58 extend freely to enable their relative sliding movement with respect to the levers 61 and 62 until the levers engage the enlarged heads 59 and 60.

Upon operation of the automobile engine, shaft 66 is rotated to turn cam 65 and thereby cause pivoting of levers 61 and 62. Upon clockwise pivoting of lever 61, or counterclockwise pivoting of lever 62, the head 59 or 60 is engaged to pull the associated rod 57 or 58 in the direction to compress the spring 44 or 45 as the case might be. Upon counterclockwise pivoting of lever 61 and clockwise pivoting of lever 62, the oversized openings 67 and 68 enable the levers to swing independently of the shafts 57 and 58, whereupon springs 44 and 45 are released to force diaphragms 40 and 41 in pumping actions toward the associated dome 38 and basin 39. The pivotal action of levers 61 and 62 merely compresses through conduit 52 normally tends to increase.

the springs 44 and 45 alternately, which latter then exert resilient force to effect the pumping action of the associated diaphragms 40 and 41. In consequence, fuel is discharged from chamber 42 by the force of spring 44. Upon the upward spring urged pumping stroke of diaphragm 40, fuel is discharged via port 47 to fuel bowl 16. All fuel in excess of engine requirements overflows the standpipe 17 and returns by conduit 52 to chamber 43 via port 53, whereupon the fuel is pumped to the fuel tank by downward spring urged pumping movement of diaphragm 41.

In order to prevent too great an excess of fuel from being pumped to fuel bowl 16 when the engine is operating at comparatively light load, means are provided for limiting the maximum movement of diaphragm 40 during the spring urged pumping stroke. As illustrated in FIGURE 2, eccentric cam 69 is keyed to a pivot shaft 70 mounted within housing 37 and extending to the exterior thereof. Keyed to shaft 70 to pivot therewith and with cam 69 is a swinging lever 71 which extends upward at a location exteriorly of housing 37 and is 'pivo-tally secured at its upper end at 72 to the outer end of a plunger shaft 73. Cam 69 directly overlies the central portion of diaphragm 40 and is shaped so that upon being pivoted counterclockwise in FIGURE 2, diaphragm 40 will be depressed. Plunger 73 extends freely through an air vent and guide opening 74 in the wall of a pressure chamber 75. The latter is partitioned by a diaphragm 76 which is normally urged to the right in FIGURE 2 by coil spring 77 disposed between housing 75 and diaphragm 76.

Variations in engine fuel requirements are detected by conduit 78 which connects pressure chamber 75 at the right of diaphragm 76 with the return flow conduit 52 at a location downstream of pumping chamber 43, thereby to regulate the pressure at the right of diaphragm 76- as a function of the return fuel flow. In order to accentuate the pressure changes in conduit 78, a restriction 79 is provided in conduit 52 at a location downstream of the latters connection with conduit 78.

In accordance with the structure of FIGURE 2, when engine load and fuel consumption drop, the return flow creased return fuel flow is indicated by an increased pressure in the portion of conduit 52 between pumping chamber 43 and restriction 79. This pressure increase is transmitted by conduit 78 to diaphragm 76 to urge the latter leftward against the force of spring 77 and cause counterclockwise pivoting of lever 71 andcam 69 to progressively decrease the pumping stroke of diaphragm 40. Thus the fuel flow to bowl 1.6 is reduced and circulation of fuel through the bowl 16 is decreased until the latter fuel flow attains an equilibrium condition determined by the new engine load requirements.

It is also apparent that upon an increase in fuel consumption by the engine, the fuel return flow in conduit 52 will decrease and the pressure in conduit 78 acting on the right side of diaphragm 76 will likewise decrease, enabling spring 77 to urge diaphragm 76 rightward to pivot lever 71 and cam 69 clockwise. The pumping stroke of diaphragm 40 and the fuel flow to bowl 16 thus increase until the system again reaches the desired equilibrium condition determined by the fuel requirements at the new engine load. The foregoing structure is independent of pressure changes in the induction conduit and depends only upon the rate of return fuel flow in conduit 52, which is thus regulated to a desired nominal value during all conditions of engine operation.

FIGURE 3 illustratesa fragmentary portion of the. carburetor and diaphragm pump of FIGURE 2 wherein cam 69, shaft 70, and lever 71 are omitted. In FIGURE 3, conduit 78 is connected with chamber 75 at the right of diaphragm 76 and also with the return flow conduit 52 downstream of pumping chamber 43 as in FIGURE 2. Port 80 vents the left side of chamber 75 to atmosphere.

The in-' The plunger 73a replaces plunger 73 of FIGURE 1 and extends rightwardly at 74a through the side wall of chamber in fluid sealing engagement and is provided with a wedge-shaped cam 81 which is insertable between lever 61 and cam 65 upon rightward movement of plunger 73a. In other respects, the structure and operation of the pump and carburetor mechanism are the same as in the abovedescribed views, so that corresponding parts are numbered the same.

During low engine loads when fuel consumption is low and the return flow fuel from chamber 43 is comparatively high, pressure in line 7 8 is high as described above and urges diaphragm 76 leftward against the force of spring 77 in FIGURE 3 to Withdraw wedge 81 from between lever 61 and cam 65. In this condition, the spring urging upward movement of diaphragm 40 in FIGURE 3 is not stressed when the lever 61 is in the horizontal position shown. Accordingly diaphragm 40' is at the upper limit of its pumping stroke and the pumping stroke will be a minimum during rotation of cam 65. As fuel consumption increases with increasing engine load, the return fiow in line 52 drops and correspondingly the pressure in conduit 7 8 drops, enabling spring 77 to urge plunger 73a and wedge 81 to the right between lever 61 and cam 65. In consequence, the lost motion between lever 61 and enlargement 59 illustrated in FIGURE 2 is decreased and the effective pumping stroke of diaphragm 40 is increased so as to supply an increased quantity of fuel to the fuel bowl 16 with increasing engine load. Obviously, sufficient flexibility will be provided in the mounting for chamber 75 or the shaft and wedge assembly 73a, 81 to enable insertion of wedge 81 between lever 61 and cam 6-5.

Referring again to FIGURE 1, instead of varying the pumping stroke by means of cam 69 or wedge 81, the pumping stroke is controlled by shifting the pivot axis 63 which in this case is supported by the short portion of a dog-leg lever 82. In other respects, the return flow carburetor and pump is the same in all views so that corresponding parts are numbered the same.

In FIGURE 1 the long leg of lever 82 is arranged to reduce the pumping stroke of diaphragm 40 upon being pivoted counterclockwise about its pivot 83 and to increase the pumping stroke of diaphragm 40 upon being pivoted clockwise. The pivot 83 connects lever 82 with housing 37. Plunger 73b extends 'slidably through the right side of housing 75 in fluid sealing engagement therewith at 74b. Vent is provided in the left side of housing 75 to facilitate movement of diaphragm 76. The movement of diaphragm 76 is controlled in accordance with engine load by conduit 78 which connects the right side of chamber 75 with the return flow conduit 52 at a location downstream of pumping chamber 43, thereby to regulate the pressure at the right of diaphragm 76 as a function of the return fuel flow. In order to accentuate the pressure changes in conduit 78, restriction 79 is provided as in FIGURE 2 in conduit 52 downstream of the connection with conduit 78.

In accordance with the structure of FIGURE 1, when engine load and fuel consumption drop, the return flow through conduit 52 normally tends to increase. The increased return fuel flow is indicated by an increased pressure in the portion of conduit 52 between pumping chamber 43 and restriction 79. This pressure increase is transmitted by conduit 78 to diaphragm 76 to urge the latter leftward against the force of spring 77 and cause counterclockwise pivoting of lever 82 to progressively raise pivot 63 and decrease the pumping stroke of diaphragm 40. Thus the fuel flow to bowl 16 is reduced and circulation of fuel through the bowl 116 is decreased until the latter fuel flow attains an equilibrium condition determined by the new engine load requirement.

It is also apparent that upon an increase in fuel consumption by the engine, the fuel return flow in conduit 52 will decrease and the pressure in conduit 78 acting on the right side of diaphragm 76 will likewise decrease, enabling spring 77 to urge diaphragm 76 rightward to pivot lever 82 clockwise and lower pivot 63. The pumping stroke of diaphragm 40 and the fuel flow to bowl 16 thus increase until the system again reaches the desired equilibrium condition determined by the fuel requirements at the new engine load.

Having thus described my invention, I claim:

1. In a carburetor for an internal combustion engine, a fuel bowl, movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return pump means in communication with said chamber for pumping said excess fuel therefrom, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means yieldingly urging said wall in said pumping strokes, an engine operated pivotal lever having an adjustable pivot axis, connecting means providing an operative lost motion connection between said lever and wall for moving the latter in opposition to said resilient means to effect an intake stroke of said wall upon pivoting of said lever in one direction beyond the extent of said lost motion and for releasing said wall for movement in a pumping stroke upon pivoting of said lever in the opposite direction, and means for adjusting the extent of said lost motion to predetermine the extent of said intake and pumping strokes comprising means responsive to the output of said return flow pump for adjusting the position of said pivot axis to predetermine the angular position of said lever relative to said connecting means.

2. In the combination according to claim 1, a fuel tank, return conduit means for returning the output of said return flow pump to said fuel tank, and supply conduit means connecting said tank and movable-wall type pumping means to supply fuel thereto, said means responsive to the output of said return flow pump including a restriction in said return conduit means upstream of said fuel tank, pressure actuated means operably connected with said pivotal lever to .adjust the position of the pivot axis thereof, and a fluid conduit connecting said return conduit means upstream of said restriction with said pressure actuated means to actuate the latter in accordance with the output of said return flow pump.

3. In a carburetor for an internal combustion engine, a fuel bowl, movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return pump means in communication with said chamber for pumping said excess fuel therefrom, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means yieldingly urging said Wall in said pumping strokes, and engine operated pivotal lever, means connecting said lever and wall for moving the latter in opposition to said resilient means to effect an intake stroke of said wall upon pivoting of said lever in one direction and for releasing said wall for movement in a pumping stroke upon pivoting of said lever in the opposite direction, adjustable movement 1 return conduit means for returning the output of said return flow pump to said fuel tank, and supply conduit means connecting said tank and movable-wall type pumping means to supply fuel thereto, said means responsive to the output of said return flow pump including a restriction in said return conduit means upstream of said fuel tank, pressure actuated means operably connected with said movement limiting means to adjust the position thereof in said path, and a fluid conduit connecting said return conduit means upstream of said restriction with said pressure actuated means to actuate the latter in accordance with the output of said return flow pump.

5. In a carburetor for an internal combustion engine, a fuel bowl, movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return pump means in communication with said chamber for pumping said excess fuel therefrom, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilent means yieldingly urging said wall in said pumping strokes, a pivotal lever, connecting means providing an operative lost motion connection between said lever and wall to enable limited lost motion pivoting of said lever independently of said wall and to move the latter in opposition to said resilient means to effect an intake stroke of said Wall upon pivoting of said lever in one direction beyond the extent of said lost motion and for releasing said wall for movement in a pumping stroke upon pivoting of said lever in the opposite direction, engine driven cam means for pivoting said lever, means for adjusting the extent of said lost motion to predetermine the extent of said intake and pumping strokes comprising wedge means adjustably insertable between said cam means and lever to predetermine the angular position of said lever relative to said cam means and connecting means, and means responsive to the output of said return flow pump for adjustably inserting said wedge means between said lever and cam means.

6. In a carburetor for an internal combustion engine, a fuel bowl, movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return pump means in communication with said chamber for pumping said excess fuel therefrom, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means yieldingly urging said wall in said pumping strokes, a pivotal lever, connecting'means providing an operative lost motion connection between said lever and wall to enable limited lost motion pivoting of said lever independently of said Wall and to move the latter in opposition to said resilent means to effect an intake stroke of said wall upon pivoting of said lever in one direction beyond the extent of said lost motion and for releasing said wall for movement in a pumping stroke upon pivoting of said lever in the opposite direction, pressure actuated means for adjusting the extent of said lost motion to predetermine the extent of said intake and pumping strokes, a fuel tank, return conduit means for returning the output of said return flow pump to said fuel tank, supply conduit means connecting said tank and pumping means to supply fuel thereto, a restriction in said return conduit means upstream of said fuel tank, and a fluid conduit connecting said return conduit means upstream of 9 said restriction with said pressure actuated means to actuate the later in accordance with the output of said return fiow pump.

References Cited by the Examiner UNITED STATES PATENTS 617,877 1/1899 Harris 103---38 1,099,449 6/ 1914 Kimball 103-3 8 1,119,029 12/1914 Mistral et a1 10338 1,293,474 2/1919 Knierim 103-38 1,860,688 5/1932 Muzzy 10338 Chilcott 103-38 Katcher 10338 Loftin 10338 X McKeggie.

Ball 26136.1 Johnson 158-37 X Ball 26136.1

FREDERICK KETTERER, Primary Examiner.

10 JAMES W. WESTHAVER, FREDERICK L. MATTE- SON, ]R., Assistant Examiners. 

1. IN A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE, A FUEL BOWL, MOVABLE-WALL TYPE FUEL PUMPING MEANS, INLET CONDUIT MEANS CONNECTING SAID PUMPING MEANS AND BOWL FOR SUPPLYING THE LATTER WITH FUEL UPON OPERATION OF SAID PUMPING MEANS, MEANS FOR MAINTAINING THE FUEL IN SAID BOWL AT A PREDETERMINED LEVEL COMPRISING AN OVERFLOW WEIR IN SAID BOWL DEFINING AT LEAST IN PART A CHAMBER ADAPTED TO RECEIVE EXCESS FUEL OVERFLOWING SAID WEIR FROM SAID BOWL WHEN THE FUEL IN SAID BOWL ATTAINS SAID PREDETERMINED LEVEL, FUEL RETURN PUMP MEANS IN COMMUNICATION WITH SAID CHAMBER FOR PUMPING SAID EXCESS FUEL THEREFROM, SAID PUMPER MEANS HAVING A RECIPROCABLE WALL MOVABLE IN ALTERNATE INTAKE AND PUMPING STROKES, RESILIENT MEANS YIELDINGLY URGING SAID WALL IN SAID PUMPING STROKES, AN ENGINE OPERATED PIVOTAL LEVER HAVING AN ADJUSTABLE PIVOT AXIS, CONNECTING MEANS PROVIDING AN OPERATIVE LOST MOTION CONNECTION BETWEEN SAID LEVER AND WALL FOR MOVING THE LATTER IN OPPOSITION TO SAID RESILIENT MENS TO EFFECT AN INTAKE STROKE OF SAID WALL UPON PIVOTING OF SAID LEVER IN ONE DIRECTION BEYOND THE EXTENT OF SAID LOST MOTION AND FOR RELEASING SAID WALL FOR MOVEMENT IN A PUMPING STROKE UPON PIVOTING OF SAID LEVER IN THE OPPSOITE DIRECTION, AND MEANS FOR ADJUSTING THE EXTENT OF SAID LOST MOTION TO PREDETERMINE THE EXTENT OF SAID INTAKE AND PUMPING STROKES COMPRISING MEANS RESPONSIVE TO THE OUTPUT OF SAID RETURN FLOW PUMP FOR ADJUSTING THE POSITION OF SAID PIVOT AXIS TO PREDETERMINE THE ANGULAR POSITION OF SAID LEVER RELATIVE TO SAID CONNECTING MEANS. 